1. Field of the Invention
This invention pertains to a chlorinator useful with dry chlorine material for automatically adding a selected amount of chlorine to water circulated through a swimming pool.
2. Review of the Prior Art
U.S. Pat. No. 3,899,425 shows, in FIG. 3 thereof, a chlorinator which is useful with the modular filter assembly shown in FIGS. 1 and 2 of the patent. This chlorinator has several desirable features, including its usefulness with dry or pelletized chlorine material, its structural and operational simplicity, and its relatively low cost, in addition to its compatibility with the modular filter assembly. The filter assembly and the chlorinator described in U.S. Pat. No. 3,899,425 are commercially available and, since first being introduced, have enjoyed considerable commercial success.
Experience with the chlorinator described in U.S. Pat. No. 3,899,425 has shown that it suffers from certain problems. No problem is encountered when water flows continuously through the chlorinator. However, in most instances, the problem occurs when the flow of water through the chlorinator is interrupted for a period of several hours every day. In a home swimming pool installation in which a circulation system is provided, the timer-controlled circulation pump operates only part of the day. When no water flows through the filter assembly with which the prior chlorinator is used, water is often trapped in the lower portion of the chlorinator chamber. This residual water within the chlorinator is in direct contact with the soluble granular or pelletized chlorine material which dissolves to form a highly chlorinated water charge in the chlorinator. When the circulation pump is next turned on, a charge of overchlorinated water is injected into the swimming pool. The result is that, despite its many advantages and great commercial success, the chlorinator described in U.S. Pat. No. 3,899,425 often presents the problem of over-chlorination of the pool and waste of dry chlorine material.
In the chlorinator shown in U.S. Pat. No. 3,899,425, the position of the valve which controls the rate of flow of water through the chlorinator chamber is set with respect to normal operating conditions which correspond to periods when the pool circulation pump is operating. Any chlorination effect occurring during periods when the circulating pump is not operating is a chlorinating effect in excess of that desired and is, as a practical matter, very difficult to control or to compensate.